/ic/ - Artwork/Critique

I don't know if this is the right place for this, but I have a specific question about the perspective of this image. It's a world map for a game, and I know it's not very good, but I'm looking for advice on perspective in particular. Something seems off to me perspective wise, but I can't really figure out how to fix it. If it's not clear, it's supposed to be an island seen from above, and the bottom left part is most accurate to the perspective I'm going for (I think). The top of the island is supposed to be flat, kind of like a rectangular cake but with some corners cut into it.

If someone could MS paint in the lines where the island's perspective should change, that would be amazing.